The present invention relates generally to methods of energizing flash lamps. More particularly, the invention relates to a method of energizing a flash lamp with a flattened and extended current pulse, or equivalently, a current pulse having a controlled amplitude and duration.
Prior art devices employing triggered flash lamps most often employ a direct current (DC) power supply with an output coupled to one or more large energy storage capacitors. The capacitor or parallel capacitors serve as a current reservoir capable of delivering a high amplitude, short duration, current pulse. Such an arrangement usually has the capacitor(s) directly coupled to a power input coupling of the flash lamp. When the flash lamp is triggered, a large amplitude current pulse, as depicted in FIG. 1B, is delivered to the flash lamp, producing a high intensity light pulse. If it is determined that the energy level of the light pulse is inadequate, the output level of the DC power supply, or the total energy storage capacitance, is increased so that a larger amplitude current pulse is available for delivery to energize the flash lamp. When considering size and cost constraints of higher power flash lamps, along with the need for very high energy light pulses in certain applications, often prior art devices operate flash lamps incorporated therein at or above peak/maximum recommended instantaneous operating levels (e.g., as specified by the manufacturer). Accordingly, the life expectancy of a typical flash lamp operated at these excessive current levels is significantly reduced.
Therefore, skilled individuals will appreciate and understand a need for new and improved means and methods for energizing flash lamps that aid in maximizing light energy output from flash lamps, without severely reducing the flash lamp operating lifetime. A full understanding of the present invention, including an understanding of a number of capabilities, characteristics, and associated novel features, will result from a careful review of the description and figures of several preferable embodiments provided herein. Attention is called to the fact, however, that the drawings and descriptions are illustrative only. Variations and alternate embodiments are certainly contemplated as being part of the invention, limited only by the scope of the appended claims.
In accordance with the invention, means and a method are provided for energizing a triggerable flash lamp. A preferred energizing method taught includes collecting and storing energy for delivery to the flash lamp. The energy that is collected and stored may be provided by a direct current (DC) power supply having an energy providing output. The collected energy is then delivered to the flash lamp in the form of a current pulse having a controlled amplitude over a short duration. Equivalently, the current pulse may be said to be xe2x80x9cflattened and extendedxe2x80x9d, when compared to typical current pulses used to energize the flash lamp when triggered. Specifically, the short duration, flattened current pulse is coupled and delivered to an energy input coupling of the flash lamp when the flash lamp is triggered, thereby producing the high energy light pulse.
The step of collecting and storing energy may most preferably be supported by including an energy storage module that is interposed between the output of the power supply module and the energy input coupling of the flash lamp. This arrangement would further preferably provide for the energy storage module to be structured having an output impedance that is matched to an input impedance of the energy input coupling of the flash lamp (when triggered and while delivering the current pulse to the flash lamp).
A preferred embodiment of the energy storage module may be provided by a charged delay line composed of a series-parallel arrangement of inductors and capacitors providing a simulated lumped-element charged delay line. When the output impedance of the charged delay line is matched to the energy input coupling of the flash lamp, the desired amplitude controlled (flattened) and duration controlled (extended) current pulse may be readily delivered to the flash lamp in order to fully energize the flash lamp while limiting the peak current to a level substantially below a maximum operating current that would typically be employed by prior art devices.